Thermostatic control for electric heaters



Jfan.10,1933. F, KUHN i 1,893,558

THERMOSTATIC CONTROL FOR ELECTRIC HEATERS original Filed Sept. 26. 1927 l Cil Patented Jan. l0, 11933 UNITED STATES PATENT OFFICE FRANK. KUHN, OF DETROIT, MICHIGAN, ASSIGNOR T0 AMERICAN ELECTRICAL HEATER COMPANY, OF DETROIT, MICHIGAN, A CORPORATION OF MICHIGAN THERMOSTATIC CONTROL FOR ELECTRIC HEATERS Application led September 26, 1927, Serial No. 222,056. Renewed July 7, 1936.

The invention relates to thermostatic controls for electric heaters having more par-v ticular reference to electrically heated laundry irons.

It is the object of the invention to obtain a construction in which there is a quick response to variations in heat; also one which permits ready attachment or detachment of the thermostatic elclnent and further one requiring but slight'modification in thc construction of the heater as designed to be without thermostaticcontrol. The invention therefore consists in the construction as hereinafter set forth. l

In the drawing I have shown lny improved thermostat as applied to a laundry iron and in which Figure l is a vertical central longitudinal section.

Figure 2 is a perspective view of the heating unit with the thermostatic switch attached thereto.

Figure 3 is a plan view thereof.

Figure 4 is a sectional elevation showing the indirect electrical connections. to the terminals S.

Figure 5 is a plan View thereof showing the bridge connection when the thermostatic switch is removed.

A is the heat distributing base of the laundry iron. B is the electrical heating unit above said base and C the pressure plate for clamping the unit to the base. D is the hood provided with the usual handle E and F is a stud rising from the base having the threaded portions F', F2 for engaging nuts G, Cr respectively clamping the plate C and hood D.

My improved thermostat is located in a recess H Within the base A preferably located centrally of said base and between the stud F and the rear end. This recess is adapted to receive a thermostatic switch which, as speciicallyshown comprises an inverted U- shaped frame member I and the contact bars J and Kvsecured thereto one of which is the -thermostatic element. The members I, J K are clamped to each other with intervenlng insulation L preferably of mica and by means of a screw stud M it also forms one ot the electrical terminals connected to. the bar K. The other terminal is a stud N which is electrically connected to the bar J While contact buttons C and P normally `electrically conneet said bars J and K. One of the buttons C is secured to a screw threaded stud Q, which -extends upward through aligned apertures in the element B, pressure plate C and hood D to a control member R outside'said hood.

The specilic construction of this thermostatic switch is '-not essential to my invention as any suitable construction may be employed `.which is distinct from the heating unit B and which is located within the recess H.

The heating unit- B is preferably of the armoured type and is centrally cut away for the passage upward of the studs M, N and Q without contact therewith. The usual terminal contacts S, and S are attached to the unit. These project through an insulator block T and outward through apertures in the hood. for engagement with the cord socket. One of the terminals S is not, however, directly electrically connected with -a resistor within the lunit but is attached to the stud M so that the current in passing through the resistor must first travel through the bar K, contact buttons O and P, bar J and stud N which latter is coupled by the connector U with a resistor. The other end of the resistor is directly connected to the terminal S so that normally the current passes in series through the resistor and thermostatic switch. Thus whenever the temperature within the base A eX- ceeds the limit at which the switch is set, the warping of the thermostatic bar will separate the contact buttons O and P which will break the circuit and prevent further heat genera-v tion.

As has been stated, one of the objects of the invention is to apply the thermostatic switch to a standard construction of iron such `as designed to be without thermostatic conand W. Thus the vonly attachment between the element and the thermostatic switchr is through these screws and by disengaging the same the element may at any time be detached; also by attaching a bridge conductor X as shown in Figure 5 the conductors `UV l. An electric laundry iron comprising a heat distributing base having a recess therein extending centrally and long1tud1nally thereof, a heating unit and a presser plate therefor arranged above said base and clamped thereto, said unit and presser plate being apertur'ed in registration with Asaid recess, supporting brackets electrically connected to opposite ends of said heating unit, plug-engaging terminal contacts mechanically supported on said brackets, one being electrically and presser plate,

Legame 3. AnA electric laundry iron comprising a', heat distributing base having a recess therein extending centrally and longitudinallyithereof, a heating unit and a presser plate therefor arranged 'above said base and clamped thereto, said unit and presser plate being apertured in registration with said recess, supporting brackets electrically connected to opposite ends of said heating unit, plug-engaging terminal contacts mechanically supported "on said brackets, one being electrically connected to and the other being insulatedV from the respective brackets, a thermostatic switch located in said recess, said switch having two studs projecting upwardly therefrom through the registering apertures in said heating unit a metallic strip secured to said insulated terminal Contact and adapted to be removably secured to onevof said studs, a second metallic strip secured to the bracket for said insulated terminal'and adapted to be removably secured to the other studY and a bridge conductor adapted tofbe secured to both of said metallic strips.

ln testimony whereof I afx my signature.

FRANK KUHN.

connected to and the other being insulated n from the respective brackets, a thermostatic switch located in said recess, terminals for said thermostatic switch projecting through the registering apertures in said un't and pressor plate, electric connections between one of said thermostatic terminals and saidinsulated terminal contact and electric connections between the other thermostatic terminal and the bracket supporting said insulated terminal.

Q. An electric laundry iron comprising a heat distributing base having a recess therein extending centrally and longitudinally thereof, a heating unitand a presser plate therefor arranged above said base and clamped thereto, said unit and presser plate being apertured in registration with said recess, supporting brackets electrically connected to opposite ends of 'said heating unit, plug-engaging terminal contacts mechanically supported on said brackets, one being electrically connected to and the other being insulated from the rcspective'bracket-s. a thermostatic switch located in said recess` terminals for said thermostatic switch projecting through the registering apertures in said unft and pressor plate, electric connections between one of said thermostatic terminals and sa'd insulated terminal contact, electric connections between the other thermostatic terminal and the bracket support-ing said insulated terminal, and a bridge conductor adapted to be secured to the aforesaid electric connections to short circuit said thermostatic switch. 

